The enhanced dedicated channel (E-DCH) is a new feature employed in the 3GPP Release 6 FDD systems. The E-DCH is an uplink transport channel. The technical purpose of the E-DCH is to improve the performance of dedicated transport channels by increasing channel capacity, increasing channel throughput, and reducing delays with the deployment of smaller CDMA spreading factors and multiple channelization codes. Further, the E-DCH permits transmission scheduling and power management for WTRUs in communication with a Node B. For example, the E-DCH facilities high speed uplink transmission capability up to 5.76 Mbps and provides a significant improvement in performance. The E-DCH also maintains the regular mobility functions of a WTRU, such as performing measurements over neighboring cells for a handover operation or preparation for cell reselection.
According to the E-DCH feature, the Node B first assigns an uplink compressed mode gap pattern to a WTRU. Then, the WTRU performs E-DCH uplink transmissions over the E-DCH. When a WTRU is configured with a 2 ms transmission time interval (TTI), the WTRU does not perform E-DCH uplink transmissions and retransmissions in TTIs that overlap with an uplink compressed mode gap. When a WTRU is configured with a 10 ms TTI, the WTRU adjusts a serving grant and scales back the power of E-DCH uplink transmissions and retransmissions in TTIs that overlap with an uplink compressed mode gap.
The Node B may assign the uplink compressed mode gaps at different positions in a radio frame. For example, the Node B may position the uplink compressed mode gaps for the purpose of inter-frequency or inter-RAT power measurement, the acquisition of a control channel of a different system or carrier, or an actual handover operation.
FIG. 1a and FIG. 1b are diagrams of a compressed mode gap position in a radio frame. A radio frame may be either a universal mobile telecommunications system (UMTS) or a wideband code division multiple access (WCDMA) radio frame.
As shown in FIG. 1a and FIG. 1b, the network may position compressed mode gaps in a radio frame using one of two methods. FIG. 1a shows a compressed mode gap 110 positioned within a radio frame 120 using a single-frame method. In the single-frame method, a compressed mode gap is positioned within a radio frame depending on a transmission gap length (TGL). FIG. 1b shows a compressed mode gap 130 positioned at the end of a first radio frame 140 and the beginning of a second radio frame 150 using a double-frame method.
The Node B assigns the uplink compressed mode gaps using a TGL. The TGL is the number of consecutive idle time slots during a compressed mode gap. The idle time slots in a compressed mode gap are consecutive whether the compressed mode gap is positioned using a single-frame method or a double-frame method. Each time slot within a radio frame is numbered (N) and ranges from 0 to 14. The number of the first idle time slot of the consecutive idle time slots is Nfirst. The number of the last idle time slot of the consecutive idle time slots is Nlast. If Nfirst+TGL≦15, then Nlast=Nfirst+TGL−1 in the same radio frame. If Nfirst+TGL>15, then Nlast={(Nfirst+TGL−1) mod 15} in the next radio frame. When the compressed mode gap spans two consecutive radio frames, the Nfirst and the TGL must be chosen such that at least 8 time slots in each radio frame are transmitted.
FIG. 2a and FIG. 2b are diagrams of a compressed mode gap position having different starting time slots in a radio frame. As shown in FIG. 2a and FIG. 2b, the Node B may position compressed mode gaps in a radio frame using one of two methods. In FIG. 2a, using a single-frame method, the Node B may position a compressed mode gap within the radio frame 220 in different positions 210, 212, 214 using a different Nfirst. In FIG. 2b, using a double-frame method, the Node B may position a compressed mode gap at the end of a first radio frame 240 and the beginning of a second radio frame 250 in different positions 230, 232, 234 using a different Nfirst.
As stated above, a WTRU configured with a 2 ms TTI does not perform E-DCH uplink transmissions or retransmissions in TTIs that overlap with an assigned uplink compressed mode gap. All E-DCH uplink transmissions or retransmissions in TTIs that overlap with the assigned uplink compressed mode gap are paused. Further, there is no need to perform any new transmission related functions, such as evolved transport format combination (E-TFC) selection, multiplexing processing, etc. Additionally, there are no hybrid automatic repeat request (H-ARQ) transmissions or retransmissions in a TTI that overlaps with an uplink compressed mode gap. If an H-ARQ process is scheduled to retransmit during an overlapping TTI, then the H-ARQ process is also paused.
Therefore, there exists the need to meet the 3GPP compressed mode operation requirements and E-DCH uplink specific transmission characteristics when a WTRU is configured with a 2 ms TTI. As a result, it would be desirable to permit detection of an overlap of E-DCH uplink transmissions or retransmissions in TTIs that overlap with an assigned uplink compressed mode gap.